1. Field of the Invention
The invention relates to ATM networks.
2. Related Art
In known ATM systems, different calls can have different requirements for transmission bandwidth. The transmission bandwidth requirement for a call is termed its "size." For example, a videoconference call is considered "larger" than a simple voice call. When selecting a virtual circuit for routing each call in an ATM network, the size of the call is considered in determining which switching nodes to select for routing each call or which through, or if the call should be rejected due to a lack of transmission capacity.
Known ATM systems determine the route for the virtual circuit for each incoming call as the call enters the ATM network. However, one problem which has arisen in the art is that this operation requires substantial computation. Accordingly, while this method achieves the goal of determining the virtual circuit for each incoming call, it has the drawback of requiring substantial resources for computation, can delay processing of incoming calls, and can therefore result in lesser throughput of incoming calls by the ATM system.
One technique to reduce the computation intensity associated with route computation is to use precomputed routes. However, precomputed routes can produce paths that are less efficient from the point of view of bandwidth utilization than routes computed dynamically. It would be advantageous to dynamically route those calls which might have a significant impact on overall bandwidth utilization in the network.
Accordingly, it would be desirable to provide a method and system for selecting routes in an ATM network, which does not require excessive dynamic route computation. This advantage is achieved in an embodiment of the invention in which most routes are precomputed, but some routes are dynamically computed in response to call size, thus call size is used to determine or help determine whether a dynamically computed route should be used instead of a precomputed route.